Tear resistant flex circuit assembly

Abstract

A medical device for sympathetic nerve ablation may include a catheter shaft, an expandable member disposed on or coupled to the catheter shaft, and a plurality of elongate electrode assemblies each constructed as a flexible circuit having a plurality of layers. The expandable member may be configured to shift between an unexpanded configuration and an expanded configuration. The plurality of electrode assemblies may be disposed on an outer surface of the expandable member. Each of the plurality of electrode assemblies may include enhanced tear resistance properties such as through the inclusion of a reinforcement structure with one or more of the layers of the electrode assemblies.

What is claimed is: 
     
       1. A medical device for sympathetic nerve ablation, comprising:
 a catheter shaft having a longitudinal axis; 
 an expandable balloon disposed on the catheter shaft, the balloon being capable of shifting between an unexpanded configuration and an expanded configuration; and 
 an elongate electrode assembly constructed as a flexible circuit having a plurality of layers, the electrode assembly mounted on an outer surface of the balloon, wherein the flexible circuit comprises a distal electrode pad and a tail extending proximally from the distal electrode pad; 
 wherein a first layer of the plurality of layers of the flexible circuit has an initial tear strength of greater than 7.5 N (1.7 lbf) according to ASTM D-1004-09. 
 
     
     
       2. The medical device of  claim 1 , wherein the first layer of the plurality of layers of the flexible circuit has a tear propagation strength of greater than 0.15 N (0.03 lbf) according to ASTM D-1922-09. 
     
     
       3. The medical device of  claim 1 , wherein the first layer of the plurality of layers of the flexible circuit has a tear propagation strength of greater than 0.2 N (0.045 lbf) according to ASTM D-1922-09. 
     
     
       4. The medical device of  claim 1 , wherein the first layer of the plurality of layers of the flexible circuit has an initial tear strength of greater than 8.0 N (1.8 lbf) according to ASTM D-1004-09. 
     
     
       5. The medical device of  claim 1 , wherein the first layer is a first insulating layer formed of a reinforced polymeric material and the flexible circuit includes a plurality of conductive traces interposed between the first insulating layer and a second insulating layer formed of a polymeric material. 
     
     
       6. The medical device of  claim 5 , wherein the reinforced polymeric material includes a plurality of fibers oriented generally perpendicular to the longitudinal axis of the catheter shaft. 
     
     
       7. The medical device of  claim 5 , wherein the reinforced polymeric material includes polymeric chains oriented generally perpendicular to the longitudinal axis of the catheter shaft. 
     
     
       8. The medical device of  claim 7 , wherein the polymeric material of the second insulating layer includes polymeric chains oriented generally parallel to the longitudinal axis of the catheter shaft. 
     
     
       9. The medical device of  claim 5 , wherein the reinforced polymeric material includes a plurality of fibers, the plurality of fibers having tapered outer diameters. 
     
     
       10. The medical device of  claim 9 , wherein the plurality of fibers are arranged such that adjacent fibers having alternating tapered outer diameters. 
     
     
       11. The medical device of  claim 1 , wherein the first layer is a microfabric layer. 
     
     
       12. The medical device of  claim 11 , wherein the microfabric layer includes a first opening and a second opening; and
 wherein the electrode assembly includes a first electrode extending through the first opening in electrical contact with a first conductive trace of the flexible circuit and a second electrode extending through the second opening in electrical contact with a second conductive trace of the flexible circuit. 
 
     
     
       13. The medical device of  claim 11 , wherein the microfabric is a woven mesh of polyimide fibers. 
     
     
       14. The medical device of  claim 11 , wherein the microfabric layer is positioned between a first insulating polymeric layer and a second insulating polymeric layer of the flexible circuit. 
     
     
       15. The medical device of  claim 1 , wherein the first layer includes poly-paraphenylene terephthalamide filaments. 
     
     
       16. A medical device for tissue ablation, comprising:
 a catheter shaft having a longitudinal axis; 
 an expandable member coupled to the catheter shaft, the expandable member being capable of shifting between an unexpanded configuration and an expanded configuration; and 
 an elongate electrode assembly constructed as a flexible circuit mounted on an outer surface of the expandable member; 
 wherein the flexible circuit includes a plurality of conductive traces interposed between a first insulating layer formed of a reinforced polymeric material and a second insulating layer formed of a polymeric material; and 
 wherein the flexible circuit comprises a distal electrode pad and a tail extending proximally from the distal electrode pad. 
 
     
     
       17. The medical device of  claim 16 , wherein the reinforced polymeric material includes a plurality of fibers oriented generally perpendicular to the longitudinal axis of the catheter shaft. 
     
     
       18. The medical device of  claim 16 , wherein the reinforced polymeric material includes polymeric chains oriented generally perpendicular to the longitudinal axis of the catheter shaft. 
     
     
       19. The medical device of  claim 18 , when the second insulating layer includes polymeric chains oriented generally parallel to the longitudinal axis of the catheter shaft. 
     
     
       20. The medical device of  claim 18 , wherein the second insulating layer includes polymeric chains oriented generally perpendicular to the longitudinal axis of the catheter shaft.